1. Field of the Invention
The preferred embodiments of the present invention relate to a motor control circuit for controlling revolutions of motors when driving the motors. More specifically, they relate to a motor driving controlling technology capable of storing information on abnormal conditions, such as, e.g., excess currents and/or overheating for the latter analysis, even after shutting off the power supply.
2. Description of the Related Art
The following description sets forth the inventors' knowledge of related art and problems therein and should not be construed as an admission of knowledge in the prior art.
When excess currents continuously flow through a motor for a long period of time, the coils may be burned off, or smoke and/or flames may be generated from the circuit.
In order to prevent these problems, in some conventional technologies, it was configured to shut down the operation of the motor when the electric current of the inverter circuit exceeded a predetermined value (see, e.g., Japanese Unexamined Laid-open Patent Publication No. H4-108491 (hereinafter referred to as “Patent Document 1”)). In another attempt to prevent the problems, it was configured to provide a storage means for storing information on specific abnormal conditions and stop the operation of the motor to prevent repeated operations in the abnormal conditions when the number of occurrences of the specific abnormal conditions exceeded a predetermined number of times (see, e.g., Japanese Unexamined Laid-open Patent Publication No. 2001-327175 (hereinafter referred to as “Patent Document 2”)).
The aforementioned Patent Document 1, however, was a technology configured to merely stop the operation of the motor when a specific abnormality occurred, and the Patent Document 2 was also a technology configured to merely stop the operation of the motor when the number of occurrences of specific abnormalities exceeded a predetermined number of times. Both of the aforementioned technologies merely focus on stopping the operations. In other words, they could stop the abnormal operation of the motor due to, e.g., excess currents, but could not determine causes of the abnormal operation.
Conventionally, the number of built-in motor drivers was one, and therefore it was possible to identify the abnormal driver which caused the abnormal operation when the abnormality occurred. In cases where there are a plurality of motor drivers, however, it was very difficult to identify the motor driver caused the abnormality. Furthermore, according the structure in which the electric power supply is shut down when abnormalities occurred, there was a drawback that the detailed information on the abnormalities could not be saved for the latter analysis.
The description herein of advantages and disadvantages of various features, embodiments, methods, and apparatus disclosed in other publications is in no way intended to limit the present invention. For example, certain features of the preferred embodiments of the invention may be capable of overcoming certain disadvantages and/or providing certain advantages, such as, e.g., disadvantages and/or advantages discussed herein, while retaining some or all of the features, embodiments, methods, and apparatus disclosed therein.